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HELP: northstar question about water in the oil

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now i know its probably the head gasket but before i tear it down i want to make sure, car runs descent, has water in oil but cant find any oil in the cooling system. seams like if its in one it should be in the other.

test ive done

1: compression. carries 210 psi ( with my gauge) on all 8

2: cooling system leak test. found that the radiator has separated at the seam, small leak.

when i bought this car the intake was completely off and i was told it just needed a starter and ignition switch, it needed a starter because he was gonna run a strait push button switch to it to start it because the vats had the starter disabled and he jacked up the ignition key lock trying to remove it to put another in thinking the key lock wasent reading the pellet on the key, turns out the vats module was bad, replaced that and put everything back together and bam, car started right up,

worse case scenario ( blowed head gasket)

now here is what else i found, there is water in the oil, i did change the oild and filter but dident really flush the system, dident have time to at that present time, wife was griping about wanting her spot back in the driveway, so i added the oil and moved it to the side yard, anyways the oil is still milky, but i dont know if its from the residual milky oil that wasent flushed, ( not sure how much water it would take to contaminate 7 quarts of oil to the point of making it milky) or if it has a head gasket leak, i drained the oil and placed another pan under it leaving the plug out and put the cooling system pressure tester back on it and was thinking that if i pressurized the system that water would find its way thru the engine and i would eventually see water draining from the pan at the plug ( correct me if im wrong)

2nd scenario ( stupid people)

when i was looking at the car the seller said that his wife just washed every bit of the car, i did find a little water in the intake valves before i re assembled the intake ( yes i blew it out) now i dont remember if the oil filler cap was off or not but the pcv valve and tube was in the trunk so im thinking if she sprayed under the hood of the car it would be possible for a sufficiant amount of water to get in the engine thru the pcv hole in the valve cover

thanks and any help is appreciated

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There is no credible path for coolant to get into the oil in a Northstar. Since nothing is completely impossible, we look at any physical possibility. One can look at the high-pressure oil lines for the cams and lifters, but the flow would be the other way, from the oil to the water - and I have never heard of that happening. The other possibility is for coolant to leak into one of the oil drain return galleries, which would require the head to be so loose that the car probably would not run, and certainly would not have excellent compression on all 8.

I'm going with the 2nd scenario.

I would change the oil again until it is clear.

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If the head gasket(s) are leaking bad enough, coolant will get into the oil. I am not sure where the thought that the coolant can't get into the oil originates. When I bought my '97 STS, the oil looked like chocolate milk.

Until you properly diagnose the problem, do not assume it is a bad head gasket.

Does the engine overheat?

Remove the surge tank cap and pressurize each cylinder with shop air while at top dead center. Listen to the surge tank - any bubbles = leaking head gasket.

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Does your radiator have an oil cooler? I have see leaky oil coolers in the radiator cause problems same for tranny coolers.

The oil has to get into the head and lifters so based on how a head gasket fails its entirely possible for oil and water to mix as KHE has experienced. It would need to be at cylinders #1 or #2 although there are drainback ports at the other end, are you experiencing a misfire in either cylinder?

I vaguely recall the guru stating that water doesnt get into oil on that NS so maybe its rare

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  • 4 weeks later...

My 97 SLS had coolant in the oil. Look like chocolate milk. Luckily was rapairable. Had 4 compromised head bolts.

I would change the oil and put the old oil into a see through jug and let it settle to see how much contamination it has. Then see what happens from there


Nice, clean, luxury= fine automobile

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